Cutter instrument for wood-turning lathes



F. s. BUCK. CUTTER INSTRUMENT FOR WOOD TURNING LATHES. APPLICATION FILED APR. l0, I915.

Patented Dec. 7, 1920.

is All! UNITED STATES FRANZ; S. BUCK, 0F

PATENT OFFICE.

SPRINGFIELD, VERMONT, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO FITZ-EMPIRE DOUBLE PIVOT LAST (30., OF ROCHESTER, NEW YORK, A CORPO- RATION OF MAINE.

CUTTER INSTRUMENT FOR WOOID TURNING LATHES.

memos.

Specification of Letters Patent.

Patented Dec. 7, 1920.

Application filed April 10, 1915. Serial No. 20,433.

T 0 all whom it may concern:

' Be it known that I, FRANK S. BUCK, a citizen of the United States, and resident of Springfield, in the county of Windsor and State of Vermont, have invented certain new and useful Improvements in Cutter Instruments for VVood-Turning Lathes, of which the following is a specification.

The present invention relates to cutting means especially adapted for use in machines for turning irregular forms from wood, such as lasts and other irregular articles. Difiiculty has been experienced in the use of the cutter head heretofore used in the last lathe due to trouble in properly mounting and gaging the cutters and to lack of interchangeability of the cutters. My invention pro vides a novel organization of cutter head which provides for the interchangeability of cutters including a simplified construction for mounting them on the cutter head, and for easy and accurate gaging of their positions.

In the drawings I have illustrated two embodiments of cutter head illustrating the principles embodied in my invention, and have shown in connection with both heads the cutters used therewith, the same sort of cutter being employed in each instance. The cutter heads here shown are respectively what iscalled the large cutter head for use in turning ordinary irregular forms in wood, and what is called the small cutter head for cutting forms which have deep concavities of short radius, such as certain special forms of last which are known as hollow sided lasts.

Figure 1 is an end view of the large cutter head.

Fig. 2 is a cross section of the cutter head taken on line 2-2 of Fig. 1 and represented as viewed from the right hand side of such line.

Fig. 3 is a development view showing the several arms of the cutter head in side, elevation and represented as placed side by side.

Fig. 1 is a diagrammatic view illustrating the paths in which the several cutters travel.

Fi 5 is a cross section through the center of orle of the cutters and the adjacent arm of the cutter head on a plane perpendicular to the axis of the head.

Fig. 6 is a perspective view of the small Referring to the drawings and first to F1gs. 1 to 4 inclusive which show the largecutter head, such head is seen to comprise a hub 10 and a number of arms 11, 12, 13, 1 1, and 15 projecting from the periphery of such hub. In the illustrated embodiment there are five such arms which project approximately radially and are spaced at equal angular intervals about the center of the hub. I may, however, construct the head with more or fewer of such arms.

Each of the arms carries a cutter, the several cutters being shown at 21 on arm 11; 22 on arm 12; 23 on arm 13; 24 on arm 14 and 25 on arm 15. These cutters and the means of attaching them to the arms by which they are respectively carried, are all alike, wherefore a description of one will sufiice for all, and the cutter 21 will be taken as the example for such a description.

Such a cutter is cup-shaped, being open at one end 26 and having an end wall or bottom 27 at the other end in which there is a passage 28. In the outer face of the end wall is a diametral groove 29 which fits, and is adapted to slide on, a rib or guideway 30 formed on the adjacent face of the arm 11 and extending longitudinallyof such arm. A bolt 31 passes through the arm 11 and through the hole 28 in the end wall of the cutter, and the head 32 of such bolt bears on such end wall and overlaps the margin of the hole. A nut 33 is screwed on the shank cutter tightly against the arm. The hole 28 is somewhat larger in diameter than the shank of the bolt to permit an adjustment of the cutter along the guideway 30, that is in and out with respect to the center of the cutter head, for a purpose which will appear later.

Externally the cutter is tapered from the open end at which the diameter of the cutter is greatest, to the end next to the arm, where the diameter is least, so that the external surface of the cutter is that of a cone. Internally the cutter is beveled at 34 near the open end so as to form a cutting edge at the margin of such open end. The outer side of such cutting edge, that is, the side more remote from the axis of the cutter head, is the part which acts on the work, and is more remote from the axis than any other part of the cutter; while the axis of the cutter itself is substantially perpendicular to a plane passing through the axis of the cutter head and intersecting the cutter. These conditions are found in each of the cutters of the entire cutter "head, and enable the cutter instrument to act on rotating irregular forms to produce curved surfaces. The cutter has one or more openings 35 in its sides-near the base thereof, that is, near the end which bearsagai-nst the arm. Two such openings, disposed on respectively opposite sides of the cutter, are here shown,-,but I may-provide only one, or more thantwo. The purposeof the openings isto permit escape of chips and also to permit passage of air and thus diminish the displacement and pressure of air when the head is running.

Byreference to Fig. 1 it will-be seen that thearms of the cutter head are ofdifi'erent lengths, thearm 11 being shortest and the other arms of successively increasing length up to the arm 15, which has the greatest length. This'same feature is shown by Fig. 4, and the latter view also shows that the outer ends of the arms are differently ofiset axially from a plane perpendicular to the axis of the cutter head. The intersectionso-f such aplane with the various arms of the cutter are shown in the different parts of "Fig.3 by the lines marked C-L in each ofthese parts. The plane chosen for illustration of this feature passes through the center of the cutter on arm 15 and to the right of the centers ofthe cutters on arms 14, 13, 12, and 11 by increasing amounts. By reason-of these differences in axial and radialoffsetting or projection,-the several cutters travel in different circular paths, the cutter ll traveling farthest to the left and nearest to the axis of the cutter head, and the other cutters being progres sively atthe right and outside of thepath of cutter 1. These paths are diagrammatically illustrated in Fig. 4, where the ci'rclesmarked 11, 12, 13, 14, and 15 represent the cutting edges of the cutters on the arms similarly marked in Fig. 1, and show the positions which these edges successively occupy when crossing the same line, such as the line 22, above the axis of the cutter head/ The line CL in Fig. 3 represents the plane which is designated by the same letters in Fig. 4.

The above described relation of the cutters is employed for machines in which the cutter carriage is fed to the left, or the work is fed to the right so that the cutting action progresses on the work from right to left. For machines in which the feed is otherwise, the direction of axial offsetting of the several cutters may be appropriately modified, within the scope of this invention. This relation causes the cutters to come into action successively on the work, the first four cutters removing surplus stock, and the last cutter 15 bringing the work piece to finished form. The cutters 11, 12, 13 and 14 may, therefore, be considered as roughing cutters and the cutter 15 as a finishing cutter. It is to be understood that the cutter is used in connection with a model and a guide which bears on the model at a point corresponding to the point on the work which is engaged by the finishing cutter, as usual in machines of the character indicated to which the presentinvention is applied.

The particular cutter herein shown has a number of advantages. First the cutters are alike, and any one may be used on any arm, whereby the manufacturer, instead of having to keep in stock a number of differenttypes of cutter for the same machine, need supply only one type. V

The circular outline of the cutter and its mode of mounting on the carrierearm enables the cutter to be turned around when one part of the edge becomes dull. Not more than half of the cutting edgeisused in one osition of the cutter sothat when 7 the used'part of the edge is dull, that portion may be replaced by the unused part of the edge upon simply loosening nut 33, turning the cutter half way around upon the bolt 31, rengaging the groove'29 with by turning it through less than 180 so as to present an unused part of the edge in the cuttlng location.

The comparatively great axial length of the cutter provides a long working life, since the cutter maybe ground back in sharpening until its edge'is brought almost to the lateral openings 35, before it is used up.

The radial adjustability of the cutter onthe arms enables it to be shifted outwardly as its edge is'carried back by sharpening, so that even though after repeated sharpenings its edge is no longer as far from the axis of the cutter head as when new, the adjustment on the arm permits the cutting side of v the edge to be brought out into the requlred' location.

After the finishing cutter has been used up by sharpening beyond the limit at which it can beadjusted for use as a finishing cutter, it may be placed on the arm of the last roughing cutter, used there tothe limit of adjustment on that arm, and used successively on the preliminary roughing cutter arms. Thus the cutters may be effectively used as long as sufficient .material remains to form a cutting edge.

The small cutter head shown in Figs. 6 and 7 consists of a central hub 40 provided with a keyway 41, which is keyed upon a spindle 42. This hub has two arms 43, each provided with a guiding rib 44 on the side which advances in the rotation of the cutter head. Each arm carries a cutter 45 having approximately the same characteristics and substantially the same form as the cutters previously described, which is secured by a screw 46 passing through a hole 47 in the closed end of the cutter and tapped into the arm 43. Cutter 45 is a cup-like piece with a tapering exterior, largest at the open end and having a cutting edge 48 at such open end. It is adapted to be adjusted outwardly on the arm as the diameter of its cutting edge becomes reduced by sharpening, in the same manner as the cutters previously described, and is otherwise arranged similarly thereto.

The two cutters on the arms of the head 40 are used as finishing cutters and both are at the same distance from the axis and are in the same zone surrounding the axis. Roughing cutters are used as a part of the cutter instrument of which the above described finishing cutter is a part. Three such roughing cutters are shown in Fig. 6. The first roughing cutter consists of a collar 49 keyed upon the shaft and having two blades 50. The second roughing cutter consists of a collar 51 and two blades 53. The third cutter consists of a collar 54 and blades 55. These collars are all keyed upon the spindle 42 with spacing rings 56, 57, between them which hold the collars at the proper distance apart. The blades on the first and second cutters project toward the second and third cutters, respectively, over the intermediate spacing rings and also project laterally from the collars on which they are respectively mounted, so that the edges of such blades extend throughout their entire length, and the paths in which the several cutters travel are contiguous to one another. The cutting edges of these blades are slightly inclined with respect to the spindle 42 outwardly toward the finishing cutter and the surfaces of revolution generated by the several edges form zones of what is approximately a continuous conical surface. The blades of the difierent cutters are, however, spaced about the axis of the shaft so as to break up the chips and distribute the cutting effort. It should be mentioned that the finishing cutter head is secured by a screw 58 which is threaded into the end of the shaft against a shoulder countersunk within the end of the head 40 and that the recess in the head 40 occupied by the head of the screw 58 is deeper than such screw head so as to admit the central part 59 of a gage 60 to be used in setting the cutters 45 both at the same distance from the axis of the spindle, so that both finishing cutters will do their shares of the work.

It is intended that the small cutter instrument be set with its axis of rotation at an acute angle to the axis of the rotation of the work, as clearly described in my prior Patent No. 1,137,117, dated April 27, 1915, and pending application Serial Number 20,432, filed April 10, 1915, in order that the bearings for the cutter spindle may clear the work and that the other advantages of the invention of the patent may be secured. The short radius of the small cutter head enables the same to cut concavities in the work of a sharper curvature than can be cut by the large cutter head.

The small cutter last described is part of.

a cutter instrument which comprises roughing cutters and one or more finishing cutters axially disposed alon the cutter instrument and projecting to di erent extents from the axis of such instrument. The same characterization applies to what I call the large cutter head, which also is a cutter instrument having roughing cutters and a finishing cutter offset from one another axially of the instrument and at respectively different distances from the axis thereof. Essentially the same character of cutter is used in both forms of the instrument, that is a cup shaped cutter having a circular cutting edge "at one end; and each cutter maybe reversed or turned when the edge at one side becomes dull, whereby to place an unused part of the edge in cutting position; and may be adjusted outwardly as the cutting edge is carried back by grinding.

What I claim and desire to secure by Letters Patent is:

1. A cutter instrument for use in a last lathe comprising a head adapted to rotate on an axis and having an arm extending transversely to the axis, a conical cup-shaped cutter mounted on the arm with the mouth of the cup extending toward the direction of rotation, the lip of the cup forming the cutting edge, and a rib and slot engaging means between the arm and cutter extending transversely to the axis of rotation, and in a plane perpendicular to the said axis, whereby the cutting edge may be adjustable to proper position as the cutter is ground, and whereby the cup-shaped cutter may be reversed and held positively in either position in order to bring different parts of the cutting edge into use.

2. A cutter instrument for use in a last lathe comprising a head adapted to rotate on an axis and having a cutter adjustably mounted thereon at a distance from the axis,

:the head having a depression with its center in the axis of rotation and which is available for gaging purposes whether the cutter be off or on its spindle, and a gage constructed and arranged to enter the depressionv and be centered thereby and .to engage the cutter Wherebythe cutter may be properly positioned.

3. A. cutter instrument for use in a last lathe comprising a head adapted to rotate on an axis and having a cutter adjustably mounted thereon at a distance from the axis, a gage for adj ustlng the cutter and interfittingmeans between the gage and head, conbeing always available for gaging purposes.

In testimony whereof- I have affixed my signature;

FRANK s. BUCK. 

